<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>计算2的n次幂</title>
</head>

<body>
	<script language="javascript">
		
	var n = parseInt(window.prompt('input'));
	var mul = 1;
	for (var i = 0; i < n; i ++) {
	    mul *= 2;
	}
	document.write(mul)
		
	</script>
</body>
</html>
